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How Fast Is Too Fast for Heart Rate?

Dear Dr. Roach: I am an 86-year-old male in good health. I take a 40-mg simvastatin and a 150-mcg levothyroxine. I exercise three times a week — one hour with weights and one hour of aerobics (elliptical and treadmill). On the treadmill, I go from a speed of 3.5 for 25 seconds to 6.0 for 25 seconds. My heart rate goes from 89 to 170 (sometimes 165 to 178) but drops back to about 89 when I return to the slower speed. I have heard that your exercise heart rate should be 212 minus your age times 80 percent. That would be 101. Does my 170 for 25 seconds sound OK? — E.N.W.

Answer: No, that sounds too fast for an 86-year-old. The formula you mention is one frequently stated, and it isn’t particularly accurate, since there is a great deal of individual variation. But 170 is very fast for an 86-year-old. I wonder if it’s accurate. A pulse monitor, using electrical impulses, is the most accurate, but even these can be fooled by electrical interference. If it really is so fast, I would worry about an exercise-induced tachycardia, and a visit to your doctor or cardiologist would be a good idea, especially if you are having symptoms of chest discomfort or shortness of breath.

Dear Dr. Roach: You discussed sleep aids and your belief that it is best to get off all of this type of medication. I am healthy, 75 (take no meds), exercise with weights, do swimming and running regularly, and since 2007 have been taking an over-the-counter sleep aid called doxylamine nightly with no apparent side effects. Do you see a problem with continuing? — A.B.

Answer: Unfortunately, I do see a problem. Odds are that you won’t have a problem taking this medication; it’s cheap and is effective for you. However, there is unequivocal, abundant, incontrovertible evidence that antihistamines like doxylamine or diphenhydramine increase fall risk. If you drive, they increase accident risk. They also can cause confusion.

Although the benefit to you from quitting is small, if I can get a lot of people to minimize their sleep medications, I know I will prevent some falls. Falls are so often the first step in a progression from health to disability that I want to do all I can to prevent them. Adequate lighting in the house at nighttime, especially between the bedroom and bathroom, avoiding obstructions like area rugs and the addition of stairway railings and tub grab bars all help reduce fall risk. Exercise programs — like the kind you are doing, but also tai chi — are great at preventing falls. So is getting your eyes checked.

No one of these interventions can prevent all falls. All of them together will prevent many. Your medication list, even a simple over-the-counter sleeping aid, is the best place to start looking to reduce risk of falls.

Dr. Roach regrets that he is unable to answer individual letters, but will incorporate them in the column whenever possible. Readers may email questions to ToYourGoodHealth@med.cornell.edu or write to P.O. Box 536475, Orl ando, FL 32853-6475.